The instant invention can be used in metallurgy, in the manufacture of refractories, ceramics and in other industries for molding products from metallic and cermet powders, molding and core sands, refractory and ceramic mixtures, etc.
The moist mixtures employed in molding are known to comprise a particulate component with binders, wetting agents and other additives, for which reason such mixtures are known as moist or bulk mixtures.
It is known in the art to mold products, e.g. slabs and items of predominantly simple shape and small height, from moist bulk mixtures by vibratory compaction thereof in a mold. The known method comprises charging a mold, made up of a case rigidly secured to a bottom and an upper punch, with a moist mixture and exerting a downward compressive lead on the mixture via the upper punch. After the mold is charged with the mixture it is subjected to an upwardly-directed vibratory shock load, while the downward compression pressure is simultaneously raised to a maximum (cf. USSR Inventor's Certificate No. 264,956, Cl. 80a, 49).
In order to raise the product density, the process of vibratory compaction is effected at a compressive load-to vertical vibratory shock load ratio of 0.4 to 0.7.
In the prior art technique, the mold is filled with the moist mixture non-uniformly due to the low mobility of the mixture as well as the lack of any means for uniformly distributing the mixture about the mold. This disadvantage is particularly significant if the products to be molded have a large height, small cross-section and an intricate configuration.
With the mold non-uniformly filled with the mixture, the molded product naturally exhibits a non-uniform pattern of density distribution with a resultant deterioration of quality. In order that the mold may be more effectively filled with the mixture during charging, the mixture is raked and levelled in the course of charging, which increases about consumption and reduces the efficiency of the molding process.
The products molded according to the known method with the mold case and bottom being rigidly interconnected and subjected to vibratory shock loading show a considerable degree of non-uniformity of density distribution. Hence, if their density is to be more uniformly distributed, it is necessary to increase the force of vibrations and the compression pressure as well as to prolong the time during which the material being compacted is exposed thereto. These factors increase in significance with the height of the product. As a result, the quality of the products deteriorates and the efficiency of the process drops. Additionally, the power consumption rises, entailing higher costs.
It is likewise known in the art to employ a vibratory-shock device for molding products from moist bulk materials, e.g. casting, molds, which comprises a vibrating frame with a vibration exciter, said frame mounting power cylinders which drive a mobile crosshead carrying an upper punch. The power cylinders simultaneously serve as guide columns for the mobile crosshead with the upper punch. The mold with the lower punch is secured directly on the vibrating frame. As the mold and the lower punch are rigidly anchored to the vibrating frame, this installation cannot be employed for molding products over 150 mm in height, because density non-uniformity in such items will exceed the allowable limit. Additionally operation of this known installation unavoidably involves hard manual labor in assembling and disassembling the mold and removing the molded products, which adds to the labor costs and detracts from the efficiency of molding.